Sri Aurobindo explains, in a brief compass, the steps that the Gita prescribes in order to achieve unity with the Brahman: “First, says the Gita, through a union of our purified intelligence with the pure spiritual substance in us by the Yoga of the Buddhi…. This spiritual turning of the Buddhi from the outward and downward to the inward and upward look is the essence of the Yoga of knowledge. The purified understanding has to control the whole being…; it must draw us away from attachment to the outward-going desires of the lower nature by a firm and steady will …, which in its concentration faces entirely towards the impersonality of the pure spirit. The senses must abandon their objects, the mind must cast away the liking and disliking which these objects excite in it,– for the impersonal self has no desires and repulsions; these are vital reactions of our personality to the touches of things, and the corresponding response of the mind and senses to the touches is their support and their basis.”
Even the physical sensations of heat and cold, hunger and thirst, pleasure and pain have to be controlled. “An entire control has to be acquired over the mind, speech and body…”
Not only the physical and vital sensations and reactions in the mind need to be controlled. The forces of desire, attachment and repulsion must also be mastered so that the seeker has a complete indifference to the objects of desire, as well as to all outer forms, forces and events. Meditation on the silent, immutable and infinite vast consciousness, and a resort to solitude, avoiding the social interactions of the world, are also part of this practice.
The forces of egoism, and initially this is primarily the rajasic ego that is filled with violent passion and lust of life and acquisition, must be conquered, and the soul released from the sense of egoism. “For the pure impersonal self which, unshaken, supports the universe has no egoism and makes no demand on thing or person; it is calm and luminously impassive and silently regards all things and persons with an equal and impartial eye of self-knowledge and world-knowledge.”
These steps are needed to free the seeker from the bondage of the ego and the attachment to the forms of the outer world, so that he may then identify with and unify with the vast impersonal Brahman “…which regards and knows but is not affected by the forms and mutations of the universe.”
Sri Aurobindo, Essays on the Gita, Second Series, Part II, Chapter 21, Towards the Supreme Secret, pp. 515-516